Use of brominated sulfurated lignin for flameproofing inflammable materials and for the production of flameproof bonded articles

ABSTRACT

Brominated lignin sulfonate and brominated kraft lignin are used for flameproofing inflammable material. The substrate may be coated or soaked with an aqeuous slurry or alkaline solution of brominated lignin sulfonate or brominated kraft lignin. It is also possible to bond particulate or fibrous inflammable material using a bonding composition containing a prepolymerisate and brominated lignin sulfonate or brominated kraft lignin.

I V KR 13 1 5623815 1- Illt t t 1111 3 862 854 e a 5M rs I Ze1gers0n et al. Jan. 28, 1975 [5 1 USE OF BROMINATED SULFURATED [56] References Cited LlGNlN FOR FLAMEPROOFING ED STATES PATENTS lNFLAMMABLE MATERIALS AND FOR 3.159.919 9/1964 Lewin 117/136 THE PRODUCTION or FLAMEPROOF 3,378,38l 4/l968 13111 111661 .1 117/137 BONDED ARTICLES 3.433.959 4/1969 Kim 260/124 3. 55.1195 7 969 N"l -R' 1 1 =1 117 37 1 Inventors Esher leieerson, Omen Moshe 3.159368 811969 6IIJ1L..TTT'...'.,..T 1171137 Rudolf Bloch, Beer Sheba, both of 3,464.921 9/1969 Erler e1 111 1 17/136 Israel Primary Examiner-William R. Trenor Attorney, Agent, or Firm-Ladas, Parry, VOn Gehr Goldsmith & Deschamps [73] Assignee: The State of lsreal, Ministry of Development, Jerusalem, Israel [22] Filed: Sept. 20, 1972 [2]] Appl. No.: 290,581 [57] ABSTRACT Brominated lignin sulfonate and brominated kraft lignin are used for flameproofing inflammable material.

[30] Forflgn Apphcauon Priority Data The substrate may be coated 0r soaked with an aqeu- Sept. 28, I971 Israel 378l2 ous slurry or alkaline Solution of bmminated lignin sulfonate or brominated kraft lignin. it is also possible [52] to bond particulate or fibrousinflammable material Int Cl [544d using a bonding composmoo contammg a [58] Fieid 147 prepolymerisate and brommated llgnm sulfonate or brominated kraft lignin.

10 Claims, N0 Drawings USE OF BROMINATED SULFURATED LIGNIN FOR FLAMEPROOFING INFLAMMABLE MATERIALS AND FOR THE PRODUCTION OF FLAMEPR'OOF BONDED ARTICLES The present invention concerns a new method for flame proofing inflammable materials by means of brominated lignin'sulfonate or brominated kraft lignin also known as alkali lignin. In one of its specific aspects the invention provides a method of bonding particulate and fibrous materials to yield articles of increased fire resistance employing as bonding agent: a composition including brominated lignin sulfonate or kraft lignin.

Lignin sulfonates are obtained'fromthe spent liquors of the sulfite process for wood decomposition while kraft lignins or alkali lignins are obtained from spent liquors, so-called black liquors, of the sulfate process for wood decomposition. Lignin sulfonate andkraft' lignin will be referred to hereinafter collectively as sulfurated lignin.

In the paper industry considerable amounts of sulfurated lignin are obtained as by-products. Hitherto several outlets for these by-products have been found and they are used among others as dispersants, binders, sequestering agents, flotation agents, emulsifiers, emulsion stabilizers, adhesives, water treating agents and the like. However, with all these outlets the amount of sulfurated lignins obtained as by-products in the paper industry exceeds the demand therefor and all paper manufacturers are constantly on the lookout for new outlets for lignin sulfonate.

It is known that sulfurated lignin, e.g., lignin sulfonate, can be halogenated, such a process being described, for example, in U.S. Pat. No. 3,438,959. In that patent specification it is stated that the haloge nated lignin sulfonates are useful as intermediates in the formation of other chemical products.

It is further known that the fire resistance of various organic materials may be improved by halogenation. Thus, in accordance with US. Pat. No. 3,092,537 the phenolic groups of organic materials of a fibrous nature containing phenolic substances including lignins, tanins and phlobaphenes are flame proofed by halogenation with a gas consisting essentially of a halogen. This procedure is highly inconvenient in that the entire mass to be flameproofed has to be submitted to the halogenation treatment. Furthermore, it has been found that the flame proofing effect obtained in this manner is unsatisfactory.

In accordance with another related process described in US. Pat. No. 3,459,588 the flame resistance ofa lignin cellulosic product is improved by chlorinating or brominating said product to a chlorine or bromine content of from 2 to 12 percent by weight and. thereafter reacting the chlorinated or brominated products with a trialkyl or triaryLphosphite or phosphonate at a tempYitiIF of I'm m 100 to 150C. This process suffers from the same drawbacks as the one disclosed in US. Pat. No. 3,092,537. 1

It has furthermore already been proposed to incorporate sulfurated lignin in fire proofing compositions. Such a method is disclosed in US. Pat. No. 3,464,921 according to which calcium lignin sulfonate is combined with various other materials such as protein powder, magnesia usta levissima, talcum powder, B Na B,O NaCl, KCL, BaCl Cal-IP0 NaHCO and a hydrophobing agent. The function of the lignin sulfonate in these compositions is presumably of a secondary nature.

In accordance with the present invention it has surprisingly been found that brominated sulfurated lignin is a highly effective fire retarding agent. Consequently, in its broadest aspect the invention consists in a method of flame-proofing inflammable material comprising incorporating in such material a brominated sulfurated lignin.

Preferably, the amount of brominated sulfurated lignin incorporated in said inflammable material is so chosen that at least 3 percent by weight of bromine is present in the final, flame-proofed product.

In accordance with one of the embodiments of the invention the inflammable material is coated or soaked with an aqueous slurry or alkaline solution of brominated sulfurated lignin and is then dried.

It has furthermore surprisingly been found in accordance with the present invention that brominated sulfurated lignin can be combined with a bonding composition, e.g., urea-formaldehyde or phenol-formaldehyde prepolymerisate, to yield a flame-proofing bonding composition. The bonding and flame-proofing capacity of the composition is based on the hitherto unknown property of brominated sulfurated lignin to be capable of copolymerizing with bonding compositions such as prepolymerized urea-formaldehyde or phenolformaldehyde to yield a stable interpolymer with flame proofing properties. Such copolymerization is presumably due to the phenolic groups of the lignin moieties.

Thus, the invention further provides flame-proofing bonding compositions containing a prepolymerisate and brominated sulfurated lignin. Examples of prepolymerisates are urea-formaldehyde and phenolformaldehyde prepolymerisates.

The above bonding compositions may be used for the production of various bonded articles of desired shapes arid sizes from particulate material such as fibres, chips, granules, sawdust and the like. Examples of such bodies are particle or chip boards, fibre boards and the like. Such bodies will be referred to hereinafter for short as bonded articles.

The invention does also provide a method for the production of bonded articles comprising admixing particulate or fibrous material with a bonding composition comprising a prepolymerisate and brominated sulfurated lignin and pressing the mixture. If desired, the mixture may be heated during pressing although in many cases this may not be required. Also a polymerization accelerator is in many cases not required. Examples of prepolymerisates are urea-formaldehyde and phenol-formaldehyde prepolymerisates.

Brominated lignin'sulfonate and brominated kraft lignin are obtained by bromination of lignin sulfonate and kraft lignin, respectively. The bromination may be effected with molecular bromine or with bromine in status nascendi obtained by oxidation from a bromide solution in which the lignin sulfonate is dispersed. The oxidation of the bromide ion to elementary bromine may be effected chemically, e.g., with chlorine, or electrochemically.

The following are examples of the preparation of brominated lignin sulfonate and brominated kraft lignin for use in accordance with the invention.

EXAMPLE 1 Lignin sulfonate or kraft lignin is suspended in water to form a 25 percent by weight slurry and bromine is added gradually. As the bromine is added the temporary colouration of the water caused by the added bromine disappears due to the bromine consumption. The

AT is a trade designation of kraft lignin obtained from the Westvaco Company.

lndulin 450a is a brominated kraft lignin obtained by bromination with liquid bromine of a 30 percent slurry reaction is terminated when bromine remains uncon- 5 of lndulin AT (see above) in water. sumed in the solution. This may be determined by any lndulin 45Gb is obtained by holding lndulin 450a in conventional method. After the completion of the reaca dessicator containing NH OH. tion the product brominated lignin sulfonate or bromi- The properties of the above products are summed up nated kraft lignin is filtered off and dried at a temperain the following Table 1. In this Table and hereinafter ture below 100C. and is subsequently ground. IO B.S.L. is used for brominated sulfurate lignin.

The mother liquor contains HBr formed in the course of the reaction and, if desired, it may be worked up for TABLE I the recovery of bromine.

Type of Total Bromine Soluble pH EXAMPLE 2 35L bromide (0.1 g/5O ml The procedure of Example 1 is repeated using, how- H2O) ever, only half the amount of bromine required. There- Orzan M3 38.0 16.4 2.4 lndulin 430 34.3 2.2 3.2 after gaseous chlorine lS bubbled through the slurry lndulin 450a 33.0 2.4 32 whereby the bromide stemming from HBr formed in lndulin 330 2'4 82 the first part of the reaction is oxidized and further brominates the lignin sulfonate or kraft lignin.

In either of the above two examples it is possible to use instead of pure water for slurrying the lignin sulfo- As mentioned it has been discovered in accordance nate or kraft lignin starting material an electrolyte soluwith the present invention that brominated sulfurated tion such as a 15% NaCl solution, a waste-HBr solution lignin copolymerizes readily with urea-formaldehyde and the like. The use of these solutions may be advantaprepolymerisate to yield a fire resistant product. Surgeons in that the losses of elementary bromine are reprisingly such copolymerization proceeds more readily duced. than if the said urea-formaldehyde prepolymerisate In the following description the invention will be were cured by itself. This follows from the following more specifically described with reference to bromi- Table II.

TABLE II Influence of B.S.L. on Time of Polymerization of Urea- Formaldehyde Type of Amount Amount of Accel- Time of Remarks B.S.L. B.S.L. Urea formalerator polymerdehyde (71) ization I00 3 3 min. 180 No polymerizution ill FOOT temp. Orzan AH-S non-brominated 10 9O 3 3 days Orzan M3 10 90 3 l min. The reaction is exothermic Orzan M3 10 90 3 min. The reaction is exothermic lndulin 430 I0 90 3 hrs. lndulin 45021 10 90 5 hrs. lndulin 430 5O 3 4 min. lndulin 430 50 50 5 min. lndulin 450a 50 50 4.5 min. lndulin 45021 30 70 10 min. pH 3.2 lndulin 450b 30 7O a few pH 8.2

days

nated lignin sulfonate termed Orzan M3, and brominated kraft lignins termed lndulin 430, lndulin 450a and lndulin 45Gb.

Orzan M3 is a brominated lignin sulfonate obtained by bromination with liquid bromine of a 30 percent slurry of Orzan AH-3 in IN K 80 solution. Orzan AH-3 is a trade designation of a lignin sulfonate product obtained from the Crown Zellerbad Company.

lndulin 430 is a brominated kraft lignin obtained by bromination with liquid bromine ofa 30 percent slurry of lndulin AT in an acidic solution containing l3.b percent by weight of HBr and 6.7 percent of HCI. lndulin From the above Table the following becomes apparent:

B.S.L. also accelerates the rate of polymerization of phenol-formaldehyde prepolymerisates, although the effect is less pronounced than in the case of ureaformaldehyde prepolymerisates. This follows from The vertical burning tests were performed by ASTM D 16-92-59 T standard. After ignition time of 3.0 secends, the flame was removed and the duration of continued flaming of material was timed.

Table III below. In an additional set of experiments lightweight card- TABLE 111 Type of Amount of Amount of Acceler- Time of Remarks B.S.L. B.S.L. phenolator polymer- (7t) formaldeisation hyde at 180C (71) (min) 100 3 36 No polymerization occurred at room temp.

Orzan M3 5 95 3 21 Orzan M3 7.5 92.5 3 18 No polymerization occurred at room temp.

Orzan M3 9O 3 l4 B.S.L. by itself, urea-formaldehyde-B.S.L. interpolymers and phenol-formaldehyde-B.S.L. interpolymers, which interpolymers are obtained from the corresponding prepolymerisate compositions as shown above, impart to inflammable materials such as wood, paper, textiles, bonded articles (as herein defined) and many more, a high degree of fire resistance. This is demonstrated by the following experiments:

In one set of experiments commercial particle boards obtained from Levidei Ashkelon, Ashkelon, Israel,- (hereinafter Ashkelon particle boards) were coated and soaked with an aqueous B.S.L. slurry.

In another set of experiments mixtures containing urea-formaldehyde, wood chips and B.S.L. wereprepared. A laboratory press of 1 cm area was used to prepare the product at pressures of 5,000 to 10,000 p.s.i. The product was in each case tested to compare its burning and hardness characteristics with a nontreated Ashkelon particle board.

The particulars of these experiments and the results obtained are summed up in the following Table IV in which U.F. stands for urea-formaldehyde. The experiments were repeatedwith Orzan M3, lndulin 430 and lndulin 450a and the results of the burning and hardness tests given are average values from the experiments. B.S.L. in Table IV thus'refers to any of the above bror ninated sulfurated lignins.

TABLE IV board was impregnated by soaking using a 9.3 percent by weight solution of lndulin 450a and Orzan M3 in IN NaOl-l. Burning experiments'were carried out on the original and the impregnated lightweight cardboard according to the standard flammability test method ASTM'D-777-46. The following results were obtained:

1. A method of flame proofing inflammable material comprising incorporating in or coating said material with an effective amount of a brominated sulfurated lignin.

Burning and Hardness Tests of Particle Boards containing B.S.L.

Type of Temp. used Pressure Burning Hardness material Composition in-pr0ducp.s.i. ASTM test Remarks tion test Barcol (sec) (935) Ashkelon 25% U.F. 180C 10000 8-34 45-50 Continues internal Particle 3% accelerator* burning 3 min. Boards 72% wood chips Ashkelon 25% U.F. Particle 3% accelerator* 180C 10000 2 Trace of internal Boards 72% wood chips burning coated with B.S.L. slurry Ashkelon 25% UP. 180C 10000 0 No internal burning Particle 3% accelerator* Boards 72% wood chips swelled in a B.S.L. slurry Laboratory IS% UP. room 5000 0 -60 No internal burning Particle l5% B.S.L. temp.

Boards TABLE 134 Continued Burning and Hardness Tests of Particle Boards containing B.S.L.

Type of Temp. used Pressure Burning Hardness material Composition in producp.s.i. ASTM test Remarks tion test Barcol (sec) (935) Laboratory 15% U.F. room 5000 55-60 No internal burning Particle 15% B.S.L. temp.

Boards 70% wood chips *a buffer solution of pH 8.8 containing NH4Cl and Nl-hOH.

Laboratory l5% U.F. room 5000 0 35-60 No internal burning Particle 15% B.S.L. temp.

Boards 70% wood chips Laboratory l2% U.F. room 5000 l2 40-48 No internal burning Particle B.S.L. temp.

Boards 78% wood chips Laboratory l5% U.F. room 5000 0.8-2 No internal burning Particle 10% B.S.L. temp.

Boards 75% wood chips Laboratory l5% U.F. room .10000 0 40-60 No internal burning Particle B.S.L. temp.

Boards 70% wood chips 2. A method according to claim 1, wherein said mate-.

rial is coated with an aqueous slurry or alkaline solution of brominated sulfurated lignin and is then dried.

3. A method according to claim 1, wherein said incorporation is an impregnation of the material with an aqueous slurry or alkaline solution of brominated sulfurated lignin and then drying.

5. A method according to claim 4, wherein said prepolymerisate is a urea-formaldehyde prepolymerisate.

6. A method according to claim 4, wherein said prepolymerisate is a phenol-formaldehyde prepolymerisate.

7. A method according to claim 4, wherein said particulate or fibrous inflammable material is wood.

8. A method according to claim 1, wherein the amount of brominated sulfurated lignin is at least 3 percent by weight of bromine present in the final, flame- ,proofed product.

9. A flameproofed article of manufacture comprising an inflammable material impregnated with an effective amount of a brominated sulfurated lignin as a flame proofing composition.

10. Articles of manufacture comprising bonded particulate or fibrous material, containing an effective amount of brominated sulfurated lignin as a flame proofing composition incorporated in the bonding agent. 

2. A method according to claim 1, wherein said material is coated with an aqueous slurry or alkaline solution of brominated sulfurated lignin and is then dried.
 3. A method according to claim 1, wherein said incorporation is an impregnation of the material with an aqueous slurry or alkaline solution of brominated sulfurated lignin and then drying.
 4. A method according to claim 1, wherein a bonded article is produced from particulate or fibrous inflammable material and said incorporating comprises admixing said particulate or bonded material with a bonding composition comprising a prepolymerisate and brominated sulfurated lignin, and pressure-curing the mixture.
 5. A method according to claim 4, wherein said prepolymerisate is a urea-formaldehyde prepolymerisate.
 6. A method according to claim 4, wherein said prepolymerisate is a phenol-formaldehyde prepolymerisate.
 7. A method according to claim 4, wherein said particulate or fibrous inflammable material is wood.
 8. A method according to claim 1, wherein the amount of brominated sulfurated lignin is at least 3 percent by weight of bromine present in the final, flame-proofed product.
 9. A flameproofed article of manufacture comprising an inflammable material impregnated with an effective amount of a brominated sulfurated lignin as a flame proofing composition.
 10. Articles of manufacture comprising bonded particulate or fibrous material, containing an effective amount of brominated sulfurated lignin as a flame proofing cOmposition incorporated in the bonding agent. 